Light management systems for optimizing performance of bifacial solar module

ABSTRACT

A bifacial solar module with enhanced power output including first and second transparent support layers, a plurality of electrically interconnected bifacial solar cells arranged between the transparent support layers with gaps between one or more of the interconnected solar cells and edges of the first and second transparent support layers, the bifacial solar cells having a first side directly exposed to solar radiation and a second side opposite the first. The bifacial solar module further includes one or more micro-structured reflective tapes positioned coincidentally with the gaps and attached to a surface of the second support layer such that light passing through the second support layer is reflected back into the second support layer at angles such that light reflecting from the tape is absorbed by either the first or second side of the bifacial solar cells.

TECHNICAL FIELD

The present disclosure relates to solar energy production. Morespecifically a solar module design incorporating light management thatincreases power output for the same or less amount of silicon solarcells.

BACKGROUND OF THE PRESENT DISCLOSURE

Solar power is accelerating as a mainstream power generation source inglobal markets. To further broaden its economic value, greaterproductivity of solar power system is desired by customers. Crystallinesolar photovoltaic systems predominantly capture light on the front sideof solar panels, on the front “face”, which can be considered“monofacial” solar panels. One method to increase power production is toharvest reflected light from the ground on the back side of the solarpanels, on to special solar cells, that are designed to harvest“bifacial” energy. Bifacial solar panels have been used in the solarindustry for over 10 years.

There are several key limitations on the design of bifacial solar panelsthat limit their utility. Initially, there is light loss through thesolar panel, around the crystalline solar cells, impacted front sidepower. Typical crystalline modules have significant areas between thecells, that are not covered by active solar cell material. Lightentering these zones on a monofacial modules is largely reflected, andscattered, by standard white backsheets, and partially recovered throughtotal internal refection (TIR) onto the front sides of solar cells. Onbifacial modules however, this light energy is lost because the backsideof the solar panel is transparent, per design, to allow the back of thecells to receive light. While this is necessary for rear sidebifaciality, front side power suffers, approximately 3-5%. This issignificant loss of power.

A second limitation is caused by lower backside irradiance at the edgeof the solar panel due to the partial shading of edge cells from frameprofile or mounting rail elements. Frames are desirable to reducebreakage of solar panels, enable a more durable long-term solar panellife, and reduce mounting system costs. However, frames have profilesthat extend beyond the lower plane of the module backsheet. As a result,cell columns near the edge of the module receive less light than cellsfurther away from the edge.

A third limitation is a result of lower backside irradiance at thecenter of the solar panel, impacting the center rows of cells, due tothe reduced availability of reflected light on the center rows of cells,attributable to the geometric relationship of incoming reflected lightbiased away from center cells rows, and/or attributable to rearstructure tube below the module center that reduce the total lightavailable to those center cell rows.

In addition to the foregoing, tracking systems are often utilized withsolar modules to reduce cosine losses from the angular displacement ofthe panels with the incident sun angle over the course of a day. Thesesystems consist of either one- or two-dimensional systems, single axisor double axis respectively, which direct the panels normal to incidentsun rays. In either case the tracking imposes limitations on the systemoutput per land area due to self-shading necessitating placement ofpanels in arrays with dead spaces where light is not directly incidenton surrounding panels. To recover some of these losses, bifacial solarmodules can be used to recapture light falling between the system rowsvia diffuse collection of ground reflected light to the panel back sidefor further power generation. However, the diffuse reflections from thesurrounding ground area are much less than optimal due to absorption andrandomly directed rays away from solar panel absorption. This reductionin power can negate the power enhancements available to bifacial solarmodules.

The present disclosure addresses all these shortcomings of the knownsystems.

SUMMARY OF THE PRESENT DISCLOSURE

A bifacial solar panel array provides an opportunity for enhancedcollection of solar energy these dead spaces using specific reflectingsurfaces. One aspect of the present disclosure describes systems andmethods for increasing power output from a solar module containingbifacial solar cells by applying light management films to the exterior,preferably back surface, of the module which causes direct and totalinternal reflection in the module to redirect light from blank regionsbetween the cells back to both active cell surfaces, cell front and backjunctions. Because large areas can be redirected, it is alsoadvantageous to increase the gaps between cells or use fractional cellsto create a concentration ratio greater than one for the module.

One aspect of the present disclosure is directed to a bifacial solarmodule with enhanced power output including first and second transparentsupport layers, a plurality of electrically interconnected bifacialsolar cells arranged between the first and second transparent supportlayers with gaps between one or more of the interconnected solar cellsand edges of the first and second transparent support layers, thebifacial solar cells having a first side directly exposed to solarradiation and a second side opposite the first, and one or moremicro-structured reflective tapes positioned coincidentally with thegaps and attached to a surface of the second support layer such thatlight passing through the second support layer is reflected back intothe second support layer at angles such that light reflecting from thetape is absorbed by either the first or second side of the bifacialsolar cells.

The micro-structured reflective tape may be adhered to the secondtransparent support layer with a UV curable adhesive material or with anacrylic material. The adhesive may be pre-attached to themicro-structured reflective tape prior to application to secondtransparent support layer.

In accordance with one aspect of the present disclosure, themicro-structured reflective tape includes prisms positioned against thesecond transparent support layer. Alternatively, the micro-structuredreflective tape may include prisms positioned on rear side of the tapeaway from a surface the second transparent support layer.

With respect to one aspect, the micro-structured reflective tapereflects light directly into second side of the bifacial cells. Themicro-structured reflective tape may also reflect light into the secondside of the bifacial solar cells and at an angle enough to totallyinternally reflect off the first transparent support layer down on tothe front surface of the bifacial cells. In one aspect of the disclosureat least a portion of light totally internally reflected off the firsttransparent support layer is further totally internally reflected offthe second transparent support layer and onto the second side of thebifacial solar cells.

In accordance with the present disclosure, micro-structured reflectivetape includes prisms having a plurality of prism angles. The pluralityof prism angles reflect light at different angles to impact the first orsecond side of the bifacial solar cells. Further the gap occupies theperimeter of the bifacial cells and the micro-structured reflective tapeincludes prism angles set to maximize light from the perimeter gap.

In one aspect of the disclosure, the gap is 1-300 mm wide across acenterline of the first and second transparent support layers dividingthe plurality of bifacial cells into two electrically interconnectedregions. The bifacial solar cells may be cut to less than whole cellsand may be electrically integrated to form two series interconnectedgroups of cells, each of these two groups connected in parallel withinthe same module.

In accordance with the present disclosure, the first and secondtransparent support layers are glass or a polymer. Further, themicro-structured reflective tape includes prisms arranged in two or morezones across the tape. Moreover, the prism shapes within each zone maybe substantially the same and at least two zones may have prisms formedwith different angles for reflecting the solar radiation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 depicts a reflective tape in accordance with the presentdisclosure;

FIGS. 2A and 2B depict a reflective tape of FIG. 1 with adhesive appliedto one side of the tape in accordance with the present disclosure;

FIG. 3 depicts a gap in the center of a solar module and solar radiationreflecting off a reflective tape of FIG. 1;

FIGS. 4A-4C depicts a reflective tape at edges and gaps between cells ona solar module;

FIG. 5 depicts a micro-structured reflective tape of the presentdisclosure with zones of different angles of reflection;

FIGS. 6A-6D depict a variety of solar modules in accordance with thepresent disclosure;

FIGS. 7A-7C depict a variety of solar modules in accordance with thepresent disclosure;

FIG. 8 depicts a solar module in accordance with another aspect of thepresent disclosure;

FIGS. 9A-9F depict a solar module and components with a reflectivecomponent of the present disclosure;

FIG. 10 depicts a linear tracking solar array with dead spaces betweenrows and random light collection;

FIG. 11A-11F depict a flexible reflective arrangement in accordance withthe present disclosure;

FIG. 12 depicts a multi-vertex flexible reflective arrangement inaccordance with the present disclosure;

FIG. 13A depicts a full parabolic system for reflecting light to theback side of a bi-facial array in accordance with the present disclosurein a first orientation;

FIG. 13B depicts a full parabolic system for reflecting light to theback side of a bi-facial array in accordance with the present disclosurein a second orientation;

FIG. 14A depicts a ground based static reflector for a bi-facial arrayin accordance with the present disclosure in a first orientation; and

FIG. 14B depicts a ground based static reflector for a bi-facial arrayin accordance with the present disclosure in a second orientation.

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE

The present disclosure is directed to systems and methods for increasingthe energy yield of bi-facial solar modules. In accordance with certainaspects of the present disclosure, the bi-facial solar modules areemployed with single axis solar tracker devices, however, otherapplications are considered within the scope of the present disclosure,including fixed position installations dual axis solar trackers andothers.

FIG. 1 shows a micro-structured reflective tape 10 in accordance withthe present disclosure. The reflective tape 10 includes a polymercarrying film 12 and UV prisms 14 formed on one surface of the film. Inat least one embodiment of the present disclosure blank spaces betweenbifacial solar cells of a solar module are covered on the back surfaceof the module by one or more of these micro-structured reflective tapes10. The reflective tapes 10 are designed to return light to the activesurfaces of the solar cells by both direct and total internal reflectivemeans, as will be described in connection with FIG. 3. The surfaces ofthe prism 14 may be coated with reflective materials to provideefficient reflection of incident light. As shown in FIGS. 2A and 2B thefilms 10 may have optically clear adhesives 16 applied either to thepolymer film 12 or the prisms 14 for adhesion to the underside of thesolar module. While application of the adhesive on the prism may providefor a lower profile and less snag likely solution, greater care must betaken in the application of the adhesives to the reflective tape 10 toensure that no bubbles form and that enough adhesive is present toensure good adhesion to the solar module. Further, in this embodimentthe polymer film is not exposed to direct solar radiation, which mayprovide some durability benefits. Alternatively, application of theadhesive to the polymer film 14 may provide some manufacturing benefitsat the potential cost of some reduction in reflective capabilities owingto the need for the polymer film to also be translucent and stillreliable despite exposure to solar radiation. The optically clearadhesives 16, as well as the polymer film 12 may have a refractive indexnearly equal to the transparent or translucent back sheet of the solarmodule. Alternatively, other refractive indices can be used for theadhesives or polymer films to provide additional optical effects. Theadhesives 16 may be UV curable and may further be acrylics.

In a further embodiment related to the embodiment of FIG. 2A the polymerfilm 12 may be removed from the prisms 14 after adhesion of the adhesive16 to the solar module. Further, in general the optically clear adhesiveshould fill between 90-100% of air gaps between the prism 14 or polymerfilm 12 and the back sheet of the solar module 20. The prisms 14preferably has a plurality of coplanar prisms with slope angle between 1and 45 degrees and draft angle between 45 and 90 degrees and a heightbetween 1 and 1000 microns. Further, the prisms 14 may be coated with ahighly reflective material. Still further the micro-structuredreflective tape prisms 14 may be formed using UV curable polymers orthermal embossing. Still further, the micro-structured reflective tapeprisms 14 may be are formed on a polymer base tape 12 which is separatedand removed from said prisms 14 after adhesion to the rear side of glass24 (FIG. 3).

FIG. 3 depicts the use of the reflective tapes applied to a back surfaceof a solar module 20. The solar module 20 includes two solar cells 22trapped between two glass sheets 24 and embedded in a bedding material26 such as Ethylene-vinyl acetate (EVA). Sunlight, graphically shown aslines 28, impact the solar module 20 and pass through the glass 24 andEVA 26. Without the reflective tapes 10, this sunlight would passcompletely through the module 20 and the vast majority of its energywould be lost to heating the air on the opposite side of the solarmodule.

In the embodiment of FIG. 3, the sunlight 28 impacts the reflectivetapes 10 and is redirected back towards the solar cells 22. Some of thisreflected light is reflected directly back to the underside of the solarcells 22 and is absorbed there. Other components of the reflected lightback into the glass 24 and again reflected back towards either the frontside of the solar cell 22 by the total internal refection (TIR), or infact reflected multiple times, a first time by the reflective tape 10, asecond time by the TIR of the glass 24, and then a third time by thereflective tape 10 before achieving an angle of reflection which impactsthe solar cell 22 and is absorbed. All these paths can be seen in thereflective paths in FIG. 3 depicted as dashed lines.

One of the advantages of applying the reflective films to the outside ofthe module is that the reflective films 10 can avoid the high heat ofthe lamination process used to construct the solar module itself. Thisallows for simple incorporation into the module process with littleimpact on the module line itself and even aftermarket retro-fit ofexisting solar modules to achieve some if not all the hereincontemplated increases in energy production.

FIG. 4A shows a further application of the reflective tape 10 along agap at the edge of the solar module 20. The solar module 20 is securedwithin an aluminum frame 30 which is common to solar modules. Thereflective tape 10 located at the gap can reflect to the edge cells ofthe solar module 20 which might be in some instances be shaded by theframe 30. As is well known shading reduces overall module output. Thereflective tape 1—at the edge can redirect the sunlight 28 which wouldnormally be lost into the backside of the solar module (or the frontside) to help eliminate shadow losses due to the frame and thus add tooverall solar module output. FIG. 4B depicts a similar cross-section ofa solar module with a frame 30 that might produce a more extreme shadingeffect on the back side of the solar module 20. FIG. 4C depicts a frontview of a solar module 20 with reflective tapes 10 formed around the gapalong edges of the solar module 20 between the outer most cells 22 andthe frame 30.

FIG. 5 depicts a further aspect of the present disclosure. Specifically,FIG. 5 shows an arrangement of the prisms 14 on the reflective tape 10that includes different zones where each zone has different attributesfor the prisms 14 formed therein. As shown, all prisms have the samebasic shape (e.g., triangular) and have a common height, (e.g., 10 mm).However, the angles of the prisms 14 may vary from zone to zone. Byhaving the prisms 14 have the same attributes within a zone,manufacturing costs can be reduced by reducing the tooling requirements.Further, each zone can be designed to perform light redirectionindependent of other zones. For instance a zone located on the edge ofthe reflective tape 10 can consist of one prism with one facet angled toredirect light directly onto the back of one of the bifacial cells, theother facet can direct light to TIR off the front glass surface toeither the front surface of another bifacial cell or to TIR again offthe rear surface of the back glass back onto the rear of the otherbifacial cell. Combinations of these zones can be used to fully recoverlight lost due to gaps between cells, frame edges, j-boxes, modulecenter areas, and other features of the solar module.

FIGS. 6A-C depict solar modules were a a gap intentionally added to thecenter of the module dividing into halves. This gap may be formed in asingle module as depicted here or may be the result of two smallermodules being used. Generally, the gap aligns with the support structurefor the modules which, like the frame, produce shading of the modulerear side causing shading and loss of potential power output. By addingthe gap and reflective tape 10 as depicted in FIG. 6B in the centerregion, sunlight is reflected into the solar cells 22 of the solarmodule 20. This results in a general power output increase because ofthe backsides of the solar cells 22 receiving greater solar energypotentially at a very low cost.

FIGS. 6B and 6C depict a further aspect of the present disclosure usinghalf cells. That is, the standard solar cells 22 as depicted in FIG. 6Acan be cut in half. As is known each solar cell outputs the same voltageregardless of its size. Current output is a function of the surface areaof a solar cell and the amount of solar radiation it can absorb. Asdepicted in FIGS. 6B and 6C the overall output power increases eventhough the surface area of the solar cells, now cut in half, isessentially the same as what is shown in FIG. 6A. Further, by adjustingspacing and utilizing more reflective tapes, the output of the solarmodule in FIG. 6C can exceed that of FIG. 6B without the addition ofmore solar cells, which are the primary cost in the solar modulemanufacturing process. FIG. 5 shows an example of combining varioustapes to loss areas to recover light from several loss areas. This canlead to maximum power output compared to modules not including tapeenhancement. Further the expectation would be that the solar module ofFIG. 6D would have an even greater output than FIG. 6C as the reflectivetapes 10 are in both vertical and horizontal directions, thus furthermaximizing the reflective the potential output. FIGS. 7A-7C depictsimilar arrangements to FIGS. 6A-6D using reflective tapes 10 in thegaps between cells and between the cells and the frame of the solarmodule.

In general, it has been calculated that a monofacial solar module suchas that depicted in FIG. 6A will have an output of about 360 W. Bymaking the same module bifacial, an increase of 30 W to 390 W can beexpected. A full cell bifacial module using reflective tapes as depictedin FIG. 7B might is a further increase to about 400 W. And a solarmodule having the configurations of FIGS. 6C and 6D can expect to havean output of 430 and 450 W, respectively.

As noted above FIGS. 6B-6D utilizes cells formed from cut whole cells.Cut cells are becoming more popular to reduce current and resistancelosses. Modules built from half cells are utilized to create moduleswhich are divided into halves as in the center gap modules of FIGS.6A-6D. The use of cut cells may afford the intentional use of gapsbetween cells to increase the proportion of reflective tape to cells.Since the reflective tape 10 is much lower in cost than cells, there isgreat potential to reduce the overall cost of solar power. At the veryleast a combination of half cells with a center gap, edge tape andrecovery from other cell gaps has the potential to produce the mostpowerful module available at significantly reduced cost, as noted abovewith reference to FIG. 6D.

In addition to the foregoing, the present disclosure contemplatesplacement of a reflective tape or other triangular reflective structure,directly on a torque tube of a solar tracker (e.g., as seen in FIG. 10).As noted in FIGS. 6A-6D, the center of a bi-facial solar module is oftenwithout solar cell coverage, placement of an triangular shaped or areflective prism tape 10 directly on the torque tube, approximately 2inches from the solar module, can effectively reflect much of the lightwhich passes through the solar module, and is not captured, back to bothsides of the solar cells. Some portion will be reflected to the rearside of the solar cell and some will be reflected to the front glass andbe captured via TIR. Further some of the sunlight may be reflected toneighboring solar modules on separate trackers (i.e., reflection botheast and west from the triangular reflector.

A further variation of this can be seen in FIG. 8 where, the prisms 14on the reflective tape can be arranged with the proper side angles (seeFIG. 5) of between 44.5 and 1 degree to allow gathering from over onefourth of a cell width depending on glass thickness. This allows theconstruction of modules 20 using quartered cells with gaps between thecells large enough to produce a net concentration ratio greater than 1.For example, cells with dimensions of 39 mm×156 mm arranged with gaps of39 mm between cells (perhaps in a linear arrangement) with films of 3 9mm in width to fill the gaps can produce a module with a ratio of 1.8 ormore depending on the optical efficiency of the cells. This can producea solar module of lower cost and enough power to lower the cost per Wattof the module by 10% or more.

In one embodiment the width of the cells is approximately the same asthe reflective tapes 10, this ratio of tape 10 to cell 22 width producesa concentration of light onto the cells of between 1.1-5× depending onwidths. Cells can be cut along both dimensions with tapes running inboth width and length directions to further increase concentration.

A further aspect of the present disclosure can be seen with reference toFIGS. 9A-9F and relate to a solar module 20 with reflective attributesbuilt into the solar module frame. FIG. 9A depicts a front perspectiveview of a solar module 20 having a frame 30 and a plurality of solarcells 22. Though shown here as full cells, half, quarter, ⅓^(rd),⅕^(th), ⅙^(th) and other dimensions may be employed without departingfrom the scope of the present disclosure. FIG. 9B depicts the backsideof the solar module 20. A support 32 can be seen extending between twosides of the frame 30 along the mid-line of the solar module 20. As willbe explained in greater detail below the support 32, functions similarlyto the reflective tapes 10 described elsewhere herein.

FIG. 9C depicts a cross-sectional view of the solar module 20, andparticularly of the frame 30. As can be seen in FIG. 9C, a projection 34extends from the frame. The projection 34 may be polished aluminum orother material from which the frame 30 is formed. The projection 34extends from sidewall of the frame 30 at an angle to the sidewall. Thisangle of the projection relative to the may be between 1 and 80 degrees,5 and 75 degrees, 10 and 70 degrees, 15 and 65 degrees, 20 and 60degrees, 25 and 55 degrees, 30 and 50 degrees, 35 and 45 degrees, and 40and 45 degrees.

In one embodiment the projection extends from the frame at about a45-degree angle. As with the reflective tape 10 described above,sunlight passes through the gaps 35 between the solar cells 22 and theframe 30 and impact the projection. The sunlight is then reflectedeither onto the underside of the solar cells 22 or back into the topglass to be reflected onto the front surface of the solar cell 22 byTIR. As will be appreciated, reflective strips 10 may also be employedin other gaps in conjunction with the projections 34.

FIG. 9D depicts a cross sectional view of the support 32 extending froman interior surface of the frame 30. The support 32 has a generallytrapezoidal shape with a flat top surface 36 and two side walls 38. Boththe top surface 36 and the sidewalls 38 are employed to reflect thesunlight that passes through the gap 37 formed in the center of thesolar module 20 onto the solar cells 22. The support 32 performs twofunctions, first the flat top surface 36 and the two angled side walls38 serve to reflect light either back into the bottom surface of thesolar cells 22 or up through the glass of the solar module 20 to bereflected on to the top surface of the solar cells 22 because of TIR.Secondly the support 32 provides additional stiffness for the solarmodule 20. This additional stiffness is becoming necessary as solarmodule manufacturers reduce the size and stiffness of the frames 30 ofthe solar modules 20 to reduce costs. Further, if desired this support32 could be retrofit into existing solar modules to provide thereflective functions.

FIGS. 9E and 9F depict the frame 30 with projection 32 and the support34 with its generally trapezoidal cross-section. The sloping sides ofthe support may have a similar angular orientation to those describedabove with respect to projection 32. As noted above, the projection 32and the support 34 may be aluminum and may be polished or painted toenhance its reflectivity.

A further aspect of the present disclosure is described herein withrespect to FIGS. 10-16. FIG. 10 depicts two a single axis solar moduletracking arrays 100. The axis of the tracking systems (about which thesolar modules 20 rotate) is generally aligned in a north/south (polaraxis) while the solar modules 20 are rotated about the axis through afixed angle range during the course of a day. In the case of bifacialsolar modules, diffuse radiation from the surrounding area providesadditional power through reflections off ground features. Due to therandom nature of the reflections only a small portion of the reflectedlight is returned to the panel for conversion and much of sunlightimpacts so called “dead zones” which return no light to the solarmodules.

FIGS. 11A-F depict two embodiments of the present disclosure showing ametalized mirror film 102, having a thickness of between 5 and 100microns. In one example the film 102 has a thickness of 50 microns. Thefilm 102 may be made of biaxially-oriented polyethylene terephthalate(BoPET) commonly sold under the tradename MYLAR® and arranged withmoving vertices that can change the slope and shape of the metalized ormirror surface to provide maximum reflection to the bifacial cells 22 ofthe solar module 20 as the solar module 20 tracks the sun during theday. The low-cost material and supporting structure and can bemechanically or electrically tied to the solar tracker 100 tosynchronize mirror shape with solar light incidence angle.

FIGS. 11A-11C depict a system with a movable lower vertex 104. In thisscenario the film 102 is rigidly attached to the trackers 100. By movingthe location of the lower vertex as the angle of incidence of the subchanges, the reflection of the sunlight also changes. In FIG. 11A, whichis closer to either a sunrise or a sunset position, the reflected lightis directed into the backside of the left most tracker 100 and thebi-facial solar modules 20 associated therewith. As the trackers 100move to the position seen in FIG. 11B, the movement of the lower vertex104 opposite the direction of movement of the sun changes the angle ofreflection of the sunlight and results in both trackers 100 receivingreflected light on the underside of the solar modules 20. In FIG. 11Cthe solar trackers 100 arrive at the noon position, with the sundirectly overhead. As a result, the reflected sunlight is equally sharedbetween the two solar modules 20 of the two trackers 100.

In a different embodiment, depicted in FIGS. 11D-11F, the lower vertex104 is held in place and does not move as the solar panels 20 arerotated by the tracker 100. Instead the upper vertices 106, which aremaintained at a constant distance from each other, are moved to ensurereflection of the sunlight into the backsides of the bi-facial solarmodules. Again, at the noon position as seen in FIG. 11F, the reflectionis equally reflected into the two trackers 100, and particularly theirsolar modules 20. Alternatively, both the upper vertices 106 and thelower vertex 104 may be movable. Still in a further embodiment, whereboth the upper and lower vertices are movable the distance between themmay be variable. In some embodiments, a tension roller (not shown) orother means is used to feed and retract film as necessary to maintainconstant tension and mirror shape throughout the daily cycle.

FIG. 12 is another embodiment of the present disclosure in which anadditional upper vertex 106 and an additional lower vertex 104 areemployed to span larger distances. Generally, one set of vertices isenough for solar trackers tracking +/−50 degrees, however, in someinstances, either with irregular spacing or where larger tracking anglesare employed, more than one set of vertices may be employed as shown inFIG. 12. The variations with respect to which vertices 104 and 106 aremovable or fixed described above may also be employed in the multiplevertex scenario depicted in FIG. 12.

FIGS. 13-14 depict a variety of mechanisms to enhance the yield of asolar array employing the reflective materials to re-direct solar energyback towards the solar panels. The mechanisms are located on either sideof the tracker 100 depending on the orientation of the solar modules 20on the trackers 100.

In the embodiment of FIGS. 13A and 13B, each tracker 100 is fitted withat least one parabolic reflector 110. The reflector 110 redirectssunlight into the backside of the solar modules 20 supported by thetracker 100. As can be seen in the progression from FIG. 13A to 13B, asthe tracker reaches a noon position, in FIG. 13B, the reflectors 110 arepositioned on either side of the tracker 100 such that both left andright sides of the solar module 20 receive reflected sunlight. Incontrast, in a more angled position, the reflectors 100 may be placed ina more biased positioned where just one of the reflectors 110 reflectssunlight onto the entirety of the solar module 20.

In FIGS. 14A and 14B one or more ground mounted parabolic reflectors 112may be employed. As can be seen in the progression from FIG. 14A to 14B,when in an angled condition, the reflector 112 re-directs sunlight ontothe backside of a single tracker 100 and solar modules 20. However, asthe sun approaches its zenith, the parabolic reflectors 112 re-directsunlight onto both parallel trackers 100 and their respective solarmodules 20.

In FIG. 14B a further embodiment is shown whereby the center portion ofthe parabolic reflector 112 can be replaced by a prism structure 114,not dissimilar to what was described above with respect to FIG. 1,though it may have different dimensions. The prism structure 114 isground mounted and substantially fixed to the ground between the twotrackers 100. Indeed, it is contemplated that the parabolic reflectors112 may be entirely replaced by a series of prism structures 114 placedon either side of the solar trackers. These prism structures may beformed of nearly any inexpensive base material, including wood,concrete, metals, plastics, etc. and coated with a layer of reflectivematerial such as the BoPET described above.

In the embodiments of FIGS. 13-14 a white fabric may be employed. Whitefabric results in reflection of light coming around the solar panel andreflect it back up to the solar modules. In some embodiments the fabricis angled. Similarly, in some embodiments, which may be fabric orlow-cost plastics, either coated with a metal or uncoated, that areformed into triangular angles that is placed between the solar trackers.For example, the ground mounted prism structure 114 may be replaced by asimple white fabric. While not an ideal solution, a portion of the lightreflected will reach the solar modules 20 and this increase poweroutput.

In yet a further embodiment, a single, or multiple, angled device isplaced between the solar trackers 100 and may be employed to reflectlight back towards the solar modules 20. In one instance the angleddevice has essentially a triangular shape. The top of the triangle isseparated from the solar module 20 by about a foot and has a slopetowards the center of the panel at a slope of about 15 degrees (possiblybetween 5 and 20 degrees). The light striking this front side isreflected into the solar module 20. On the back side of the triangularelement there may be a slope of about 65 degrees, this then reflectslight striking the backside of the triangular device into the solarpanels of the neighboring tracker.

Although embodiments have been described in detail with reference to theaccompanying drawings for illustration and description, it is to beunderstood that the inventive processes and apparatus are not to beconstrued as limited thereby. It will be apparent to those of ordinaryskill in the art that various modifications to the foregoing embodimentsmay be made without departing from the scope of the disclosure.

We claim:
 1. A bifacial solar module with enhanced power outputcomprising: a first transparent support layer and a second transparentsupport layer; a plurality of electrically interconnected bifacial solarcells arranged between the first transparent support layer and thesecond transparent support layer with gaps between one or more of theplurality of interconnected bifacial solar cells and edges of the firstand second transparent support layers, the plurality of interconnectedbifacial solar cells having a first side directly exposed to solarradiation and a second side opposite the first side; and one or moremicro-structured reflective tapes positioned coincidentally with thegaps and attached to a surface of the second transparent support layersuch that light passing through the second support layer is reflectedinto the second support layer at angles such that light reflecting fromthe one or more micro-structured reflective tapes is absorbed by eitherthe first side or the second side of the bifacial solar cells, whereinthe one or more micro-structured reflective tapes include prisms havinga triangular profile defining a base extending across a width of the oneor more micro-structured reflective tapes and first and second sidesurfaces, the prisms of the one or more micro-structured reflectivetapes are arranged in two or more zones contiguously across the width ofthe one or more micro-structured reflective tapes, wherein the first andsecond side surfaces of prisms in a first zone of the two or more zonesdefine interior angles relative to the base that are different thaninterior angles defined relative to the base by the first and secondside surfaces of prisms in a second zone of the two or more zones. 2.The bifacial solar module of claim 1, wherein the one or moremicro-structured reflective tapes is adhered to the second transparentlayer with a UV curable adhesive material.
 3. The bifacial solar moduleof claim 1, wherein the one or more micro-structured reflective tapes isadhered to the second support layer with an acrylic material.
 4. Thebifacial solar module of claim 1, wherein an adhesive is pre-attached tothe one or more micro-structured reflective tapes prior to applicationto the second transparent support layer.
 5. The bifacial solar module ofclaim 1, wherein the one or more micro-structured reflective tapesincludes prisms positioned against the second transparent support layer.6. The bifacial solar module of claim 1, wherein the one or moremicro-structured reflective tapes includes prisms positioned on a rearside of the one or more micro-structured reflective tapes away from thesurface of the second transparent support layer.
 7. The bifacial solarmodule of claim 1, wherein the one or more micro-structured reflectivetapes reflects light directly into the second side of the plurality ofinterconnected bifacial cells.
 8. The bifacial solar module of claim 1,wherein the one or more micro-structured reflective tapes reflects lightinto the second side of the plurality of interconnected bifacial solarcells and at an angle enough to totally internally reflect off the firsttransparent support layer down on to a front surface of the plurality ofinterconnected bifacial cells.
 9. The bifacial solar module of claim 8,wherein at least a portion of light totally internally reflected off thefirst transparent support layer is further totally internally reflectedoff the second transparent support layer and onto the second side of theplurality of interconnected bifacial solar cells.
 10. The bifacial solarmodule of claim 1, wherein the plurality of prism angles reflect lightat different angles to impact the first side or the second side of theplurality of interconnected bifacial solar cells.
 11. The bifacial solarmodule of claim 10, wherein the gaps occupy a perimeter of the pluralityof interconnected bifacial cells and the one or more micro-structuredreflective tapes includes the plurality of prism angles set to maximizelight from the gaps at the perimeter.
 12. The bifacial solar module ofclaim 1, wherein the gaps are 1-300 mm wide across a centerline of thefirst transparent support layer and the second transparent support layerdividing the plurality of interconnected bifacial cells into twoelectrically interconnected regions.
 13. The bifacial solar module ofclaim 1, wherein the plurality of interconnected bifacial solar cellsare cut to less than whole cells.
 14. The bifacial solar module of claim1, wherein the plurality of interconnected bifacial solar cells are cutinto half cells and are integrated to form two series interconnectedgroups of half cells, each of these two series interconnected groupsconnected in parallel within the same module.
 15. The bifacial solarmodule of claim 1, wherein the first transparent support layer andsecond transparent support layer are glass or a polymer.
 16. Thebifacial solar module of claim 1, wherein prism shapes within each ofthe two or more zones are substantially the same and at least two zoneshave prisms formed with different angles for reflecting the solarradiation.
 17. A bifacial solar module with enhanced power outputcomprising: a first transparent support layer and a second transparentsupport layer; a plurality of electrically interconnected bifacial solarcells arranged between the first transparent support layer and thesecond transparent support layer with gaps between one or more of theplurality of electrically interconnected bifacial solar cells and edgesof the first transparent support layer and the second transparentsupport layer, the plurality of interconnected bifacial solar cellshaving a first side directly exposed to solar radiation and a secondside opposite the first side; and one or more micro-structuredreflective tapes positioned coincidentally with the gaps and attached toa surface of the second transparent support layer such that lightpassing through the second transparent support layer is reflected intothe second transparent support layer at angles such that lightreflecting from the one or more micro-structured reflective tapes isabsorbed by either the first side or the second side of the bifacialsolar cells, wherein the one or more micro-structured reflective tapesinclude prisms arranged in three or more zones contiguously across awidth of the one or more micro-structured reflective tapes, each zone ofthe three or more zones defining prisms having interior angles that aredifferent than interior angles of the prisms of the remaining zones ofthe three or more zones of the one or more micro-structured reflectivetapes.